Sound – VCO

Sound – The Voltage Controlled Oscillator or VCO
Before we can hear anything, we would need a tone generator.  A tone is basically an oscillating (vibrating) waveform. There are three distinct categories:

Simple waveforms
Well known examples are the sine, saw and block waves.  Bob Moog made them famous and there’s nothing like the Moog sound on a bit of reverb.

Complex waveforms
Obvious examples from the synth world are the pink- and white noise. Less obvious examples are the shapes of a wavetable synth, the sound of a violin or sax and the human voice. Recorded music is a complex waveform too.

Frequency Modulated (FM) Waveforms
Many complex waveforms are the result of adding two or more waveforms together so a new sound is created.

Voltage Control
OK, we have an oscillator that does BZZZ all the time.  This is becoming very boring quickly, so we need to feed it a note to play.  And voltage is the way to do it, basically with 1 volt per octave.  So we can control the note by changing the voltage. This can be done smoothly (by turning the knob). It can be done by giving it a specific control voltage (CV) that matches a specific key.  So a CV connection on a VCO will let you control its pitch. Sometimes this CV connection is labelled V/Oct which is the common norm so you have nothing to worry about. There’s also a V/Hz system created by the famous mr. Donald Buchla who pioneered the synthesis world  half a century ago. So you could need a ‘converter’ if you happen to own a vintage Buchla and want to hook it up. 

Synthesis types
Vintage synths use the subtractive technique: you start with a simple waveform and then you start ‘cutting away’ the sounds you don’t like.  This is done by filters and envelopes. Great examples of these synths are the Moog and the Jupiter 8.

Additive synths take the same simple waveform, but they add a second waveform to let mother nature make a new sound (FM). In Western music, instruments are tuned at 440 Hz (A4). You can make it drop an octave by subtracting half of it. You can rise an octave by multiplying it by 2.  Regular synths allow you to do that by turning the frequency knob. With FM synthesis, you’ll have to add a second waveform that will transform the original into a new waveform.  So if you ‘add’ a 440 Hz (A4) to itself, you’ll double the frequency to 880 Hz (A5).  Yes, doubling the frequencies takes you an octave higher.  If you want to go down an octave, you’ll need to ‘add’ 220 to it.  This also shows the relationship between nice sounds that fit the harmonic scale of a piano keyboard. Metallic and percussive sounds don’t have a clear note. You’ll get these sounds by experimenting with values out of that scale. Some legendary additive / FM synths are the Yamaha DX7 and the Synclavier.

And then there’s sampling. Personally I love sampling, because in theory, you could use any waveform and blend/mix/modulate it into something else.  In the early days when we where still 16 bit and had 65535 values to code a simple waveform (the real time analog version has theoretically endless values) you could hear the difference between a smooth VCO and his jagged cold digital counterpart. But now we are 32 bit with plenty of values (billions) to emulate the moog sine. So sampling has become really powerful. However, there will always be a difference in sound when you make analog sounds interact. You can have unpredictable side effects with full analog gear.  It’s much harder to program unpredictable side effects :).  A real 808 drum machine sounds much fatter than its digital counterparts. Yes I know that doesn’t make sense with 32 bit resolution and 192 hz sampling frequency. But KNOWING it isn’t the real thing makes all the difference.  Maybe this explains why vintage gear is so expensive. But if you’re into sound design, a sampler must be on your list. Famous samplers from the old days are the CMS Fairlight and the Emulator from E-mu Systems.  Many Emulator tech has returned to the modular stage by Rossum Electro-Music – the Assimilator.
Resistance is futile.

Some considerations
The best starting point for your quest is Google.  Just search for ‘best VCO’ and you’ll get some really good suggestions from the experts.  If you go modular, you’ll probably want FM synthesis sooner or later, but it may be a good idea to start with simple waveforms first.  A really clever VCO is the Mutable Instruments Plaits (pronounced as Plats) which can give you a vast array of sounds and noise.  Really affordable too. If you’re into vintage, the Moog Mother 32 is a great starting point with a legendary sound. And it comes with a filter, amplifier, sequencer and patch panel to connect / integrate other modules. But if you’re into something special, you should also check out the MakeNoise DPO dual oscillator.  The Plaits and 32 are very musical. The DPO is pure evil, hard to tame and can’t really shine without  a VCA and an Envelope. But these are two other crucial parts of the basic synth. If you’re into sampling, the TipTop Audio ONE is a very affordable choice.  It doesn’t record sounds by itself, but you can load your own sounds on an SD and put it under Voltage Control. You’ll find the Rossum Assimilator on the other side of the feature scale but this also enables you to record loops and control voltage.  So imagine you have all kinds of stuff running to modulate your VCO, then this thing allows you to record all these modulation commands. Then you can unplug everything and replay the recording. This also works with sequences, random stuff, everything.  This is really cool because most modulars are on Altzheimer when you unplug the patches.

My choice? Everytime I have to choose I hear Freddie Mercury in the back of my head, singing ‘I want it all and I want it now’.  And he has a point. Life is too short for just a Mother 32 with only one oscillator (no FM). So here’s a link to my DreamMachine VCO modules that can give me an incredible collection of sounds.